There has already been prepared a number of copolymers of esters of acrylic or methacrylic acids. These esters copolymerize with a great number of types of monomers for example, ethylene, styrene, acrylonitrile, vinyl chloride or vinyl acetate.
According to the monomers employed, these copolymers can be utilized for the production of molded objects, paints or adhesives.
Certain of these copolymers can also be utilized as additives to lubricating oils. This is notably the case of copolymers of esters of acrylic or methacrylic acid with basic monomers containing two atoms of nitrogen such as N-vinylimidazole or one atom of nitrogen and one atom of oxygen such as N-vinyl-pyrrolidone.
The addition of these nitrogen copolymers to oils produces an improvement in their index of viscosity.
The improvement of this index viscosity, determined according to the standard AFNOR NF T-60-136 shows that the effect of temperature on the viscosity is reduced.
These copolymers can additionally reduce the flow point of the oils and due to the polarity and the basicity of the nitrogen monomer, provide a dispersing and detergent power in the additive, thereby contributing to the cleaning of a motor lubricated by these oils.